Isotope separator



Feb. 23, 1960 J. SLEPIAN 2,926,252

ISOTOPE SEPARATOR Filed June 24, 1957 s Sheets-Sheet 1 e A Fbt entiql Feb. 23, 1960 J. SLEPIAN 2,925,252

I ISOTOPE SEPARATOR Filed June 24, 1957 3 Sheets-Sheet 2 w Jose l "lliian Feb. 23, 1960 J. SLEPIAN 2,925,252

ISOTOPE SEPARATOR Filed June 24, 1957 3 Sheets-Sheet 3 Conductor 2| INVENTOR Joseph Slap/an Conducior 23 United States r am- 6 ISOTOPE SEPARATOR Joseph Slepian, Pittsburgh, Pa. Application June 24, 1957, Serial No. 667,413 15 Claims. 01. 250-419 This application relates to electric discharge apparatus and has particular-relation to apparatus for separating isotopes. U.S. Patent 2,752,503, granted June 26, 1956, of which'the present invention is an outgrowth is incorporated in this application by reference. This application is a continuation-in-part of application Serial No. 519,374, filed July 1, 1955, and now abandoned. The patent relates to apparatus for separating isotopes in which a short are including'ions of the isotopes and electrons'is produced in a magnetic field parallel to the arc and the ions and electrons are subjected to an electric field produced in the space including the arc. The reaction of these electric and magnetic fields and the elect'rodes'producing them with the ions and electrons'effects the separation. p

It is an object of this invention to provide a novel structure for producing the electric field in'an isotope separator of the type disclosed in the patent and it is another object of this invention to provide apparatus for producing a magnetic field which is particularly suitable for use with the novel electric ifield producing structure.

In accordance with this invention, the arc is generated between two electric field conductors which we shall call the expander electrodes near one end of these conductors. Specifically, the expander conductors may diverge or flare out and the arc may be produced between the expanders near the end where the distance between the expanders is a minimum. i

I In accordance with a further aspect of this invention, the magnetic field for apparatus in which the electric field producing conductors diverge is produced by an electromagnet having generally triangular pole pieces at the opposite ends of the region defined between the conductorsl It is well known that an arc is restricted'by a parallel magnetic tfield, and that few conducting particles will reach from the are into the surrounding space, unless a radial electric field exists which will draw the particles out. To effect this the electrodes of the are at the top and bottom of the vessel containing the arc and other electrodes, have around them circular plate electrodes maintained at a moderate negative potential relative to the arc, and these circular plate electrodes extend only as far as the two flaring expander conductors at their minimum distance apart. These circular plate electrodes draw a small positive ion current from the arc, and reject electron current, and thus force the electrons, with accompanying ions over toward the'expander conductors. The remainder of the end electrodes perpendicular to the magnetic field above and below the expander plates are insulated, so that they draw no current, neither an excess of positive ions, nor an excess of electrons, but only 'ions and electrons in equal amounts. The end electrodes maybe made up of segments, each ofwhich must he'insulated. I

At the end where the distance between the expanders is a maximum a plurality of slats or plates extend be-. tween the expanders. These slats or plates are nearly radial in accordance with the specific aspects of this invention. So that the neutral molecules may pass through deposited predominately on the slats adjacent this negative conductor.

This invention in one of its important specific aspects arises from the realization that where the isotope collect-' ing slats are radial the deposit on the slats depends on the diffusion of the isotope ions to the slats. In the region of the slats the random velocities superimposed on the mean velocity of the ions (which is radial) 'is very small so that the diffusion rate is very small.

- In accordance with the important specific aspect of this invention pairs of adjacent slats are conductively connected. The effect of this connection is to produce a field distribution such that the isotope ions become deposited rapidly on the slats but the neutral molecules pass through the spaces between the slats. In the region between connected adjacent plates, there is in eifect a field" (H v where H is the magnetic field and v the velocity of the ions) positively moving the ions towards the plate nearest'the positive conductor. Between the next adjacent unconnected plates there is a reverse electric field'of twice the magnitude of the last mentioned field positively-moving the ions towards the sameplate;

The novel features considered characteristic of this invention are disclosed generally above. The invention itself both as to its organization and its method of operation, together with additional objects and advantagesthereof, will be understood from the following description of a specific embodiment when read in connection with the accompanying drawings, in which:

Figure 1 is a view in transverse section showing an embodiment of this invention;

Fig. 2 is a view in section taken along line II -II of Fig. l;

' Fig. 3 is a diagrammatic view illustrating the operation of this invention; and

Fig. 4 is a graph illustrating the operation of this irivention.

The apparatus shown in the drawings comprises a container 11 in the form of a prism of generally triangular cross-section. The container 11 may. have curvilinear sides as shown, or it may have straight sides. The container is preferably composed of a non-magnetic metal and is provided with an exhaust tubulation 13' through which it may be evacuated to the pressure disclosed in the parent application in the manner disclosed therein.

A'pair of expanders 21'and 23, the expander "electrodes, are mounted within the container 11. These con duotors diverge from the apex 25 of the container to the opposite side 27 extending along the sides 29 and 31 joining the apex to the side 27; The expanders 21 and 23 are suspended from the sides 29 and 31 by brackets or studs (not shown) in a manner well known in the art. While the cross-section of the expanders 21 and 23 may be of any diverging contour, it is preferable that they be of such contour that the slope of the curve of the conit is further desirable that the contour of the expanders satisfy the equation faces s52 where s is the distance along the contour of a conductor, x is the distance between the conductors measured in a direction perpendicular to a center line CL between the conductors, and k is-a constant and d the differential operator. Where a high enrichment of the separated isotopes is desired, the distance L between the expanders 21 and 23 in the region where thespacing between them is .a minimum should be as small a fraction as practicable of the distance L between the conductors where distance is a maximum. The space bounded by the expanders 21 and 23 should be closed electrostatically by shield plates 41 and 43 of non-magnetic conductive material extending a short distance from the edges of the conductors 21 and 23 but insulated from them. The plates 41 and 43.may be singleplates or they may .be sets'of overlapping plates asshown (Fig. 1).

At the end where the distance between expanders 21 and 23 is a maximum, a plurality of slabs or slats or plates 71 extendbetween the conductors. These plates are desirably spaced a relatively short distance from each other and extend with their planes radial with respect to the are A as a center. In accordance with this invention pairs of adjacentplates 71 are connected by conductors 72. The plates 71 serve to collect the isotope ions.

.To produce the ions of the isotopes an are A is produced within the region between expanders 21 and '23 near the end where the distance between them is a minimum. This are A is fired between a-pair of electrodes 51 and 53 supported from holders 55 and 57 sealed through insulators 59 and 61 in the container 11 and passing through potential impressing rings 201. The electrodes are of the type disclosed in Patent 2,752,503 and are energized in the manner disclosed in Patent 2,752,503.

A field adapted to act on the ions and eleotronssent out from the arc A by the radial field from the circular plate electrodes 201, is produced .by impressing a potential between the expanders 21 and 23. This potential may be impressed in the manner disclosed in Patent 2,752,503 from a suitable source 81.

.The are A and the ions and electrons from it are subjected to a magnetic field parallel to the arc and "which isproduced by an electromagnet 91 having substantially triangular pole pieces 93 and 95 extending over each end of the region between the expanders 21 and 23. The magnet is excited by coils 97 and 99 which may also be of generally triangular form and which enclose thepole pieces.

.In separating isotopes in the apparatus disclosed "the electric field is applied between the field producing-expanders 21 and 23, the magnet 91 is excited, and the arc A is fired. The are is of the type disclosed in .Patent 2,752,503. The ions and electrons produced in theme are subjected to the magnetic field produced by the magnet 91 and to the electrical fieldin the region between the expanders 21 and 23.

The operation of the apparatus is .illustratedinFig. 3. In this view the'field producing expanders 21 and 23 are shown in cross-section. Themagnetic field is designated by'H, the'velocity of the positive ions by v, the velocity of-theelectrons by u, and the field by E. The .field .E satisfies.

where, .s is the distance along any'lline'betwetsnthe expandersll and.23 and V .is theimpresse'd voltage between the expanders.

-Atithe negative expander23 the etfect .o'f'E is to cause electrons to 'leave the neighborhood of the expander, the remaining free positive ions then flow along expander "23 towards the slats 71 in the intense electric field in the neighborhood of the plate. Similarly positive ions are repelled from the expander 21 and the free electrons in the neighborhood of the expander flow in the corresponding intense electric field along the expander 21 towards the slats. The flow along the expanders 23 and 21, respectively is produced by the interaction of the magnetic field H on the free ions or free electrons. The result is that current as represented by the outermost loop in Fig. 3 flows in the space. (Current cannot flow through the slats.) Beyond this current loop, that is, near the slats 71, the current is zero. "in this region the velocity of the ions is equal to the velocity of the electrons. Alsoin this region and the electrons and theions flow radially.

The effect of the interaction of the field on theisotope ions is as is demonstrated 'in Patent 2,752,503, such that the heavier isotope ions tendto flow toward the positive expander 21 and the lighter isotopes toward thenegative expander 23. The flow is indicated by arrows in Fig. 3. Because of this discrimination in the ion flow to the conductors, a separation is effected and as is shown in Patent 2,752,503, this separation is substantial.

The isotope ions and electrons predominately flow into the region between the plates 71. Because of the connection .of the slats in pairs the ions are deposited on alternate slats andbecause of the orientation of the slats the neutral molecules pass through the slats. The ions are deposited on both sides of the slat of each connected pair which .is nearest the positive expander 21.

The distribution of the potential impressed on the slats is .shown in Fig. 4 in which potential is plotted vertically and distance as .measured by the spaces between slats .is plotted horizontally. The slats 71 are at the potentials corresponding to Fig. 4 not by reason of any conductive connections between the expanders 23 and 21 and the slats 71 but by reason of the position of the slats inthe space between the ends of expanders 23 .and 21.

The light horizontal lines represent the potentials on the expanders 21 and 23. The broken-line curve represents the potential distribution in the space where the slats are disposed in the apparatus of Patent 2,752,503. The heavy sawtooth curve having horizontal and sloping sections represents the potential in the space between the successive connected pairs, and unconnected pairs of slats 71 in apparatus in accordance with this invention. As indicated the deposit is on the more negative of each pair of unconnected slats. The slats 71 on the siderof thenegative expander 23 are progressively more enriched in the lighter isotope and the slats on the side of ,positive expander 21 are progressively more enrichedin the heavier isotope. The neutral molecules pass through.

While this invention .has been disclosed herein as appilcable to apparatus in which the arc is produced between the field producing expanders 21 and 23, it is in its broader aspects applicable to apparatus of other types, for example,'tothe apparatus disclosed in Patent 2,752,- 503, 'Slepian.

While specific embodiment of this invention has been disclosed herein, many modifications thereof are feasible. The invention, therefore, is not to be restricted except insofar'as is necessitated by the spirit of the prior .art.

I claim-as my invention:

1. Apparatus .for separating isotopes 'ofa material including an evacuated container, means for producing .in said container an are including ions of said isotopes, means for impressing a magnetic field generally parallel to said are, .a zpair of oppositelydisposed expandershaving their surfaces generally parallel to said are, said expandersenclosingsaid arc in the region between them S said slats extending radial to said are as a center, adjacent pairs of slats being eonductively connected.

2. Apparatus for separating isotopes of a material including an evacuated container, means for producing in said container an are including ions of said isotopes, means for impressing electric fields including a pair of diverging expanders having their surfaces generally parallel to said are and means for impressing an electric potential between said expanders, said expanders enclosing said are between them near the end where the distance between them is a minimum, and a plurality of conducting slats extending between said expanders near the other end thereof, the planes of said slats extending radial to said arc as a center, adjacent pairs of slats being conductively connected.

3. Apparatus according to claim 2 characterized by the fact that the expanders flare out from the region where the are is produced, the cross section of each expander being a curve having a continuous slope.

4. Apparatus according to claim 1 characterized by the fact that the expanders diverge and the arc is produced near the region between said expanders where the distance between them is a minimum.

5. Apparatus for separating isotopes of a material ineluding an evacuated container, means for producing in said container an are including ions of said isotopes, means for impressing a magnetic field generally parallel to said are and means for impressing circumferential electric fields around said are, each said field being maintained at the same polarity, the said apparatus being characterized by means for impressing electric fields including at least a pair of oppositely disposed expanders, the are being produced near one end of the region between said expanders, and by a plurality of slats extending between said expanders near the other ends thereof, the planes of said slats extending radially with respect to said are and alternate slats being conductively connected.

6. Apparatus for separating isotopes of a material including an evacuated container, means for producing in said container an are including ions of said isotopes, means for impressing a magnetic field generally parallel to said are and means for impressing circumferential electric fields around said are, the vectors representing said electric fields lying in planes generally perpendicular to said are, each said field being maintained at the same polarity, the said apparatus being characterized by means for impressing electric fields including a pair of diverging expanders, the are being produced between said expanders near the end where the distance between them is a minimum.

7. Apparatus according to claim 6 characterized by the fact that the expanders flare out from the region where the arc is produced, the cross section of each expander being a curve having a continuous slope.

8. Apparatus according to claim 6 characterized by a plurality of spaced slabs insulated from each other and from the expanders extending between the ends of the expanders in the region where the distance between them is a maximum.

9. Apparatus according to claim 13 characterized by the fact that the expanders diverge and the are is produced near the region between said expanders where the distance between them is where s is the distance along said expander from the end where it is nearest the other expander, x is the distance between the expander measured along a line perpendicular to the center line between them, k is a constant and d is the difierential operator.

13. Apparatus for separating isotopes of a material including an evacuated container, means for producing in said container an are including ions of said isotopes, means for impressing a magnetic field generally parallel to said are and means for impressing electric fields around said are, the vectors representing said electric fields lying in planes generally perpendicular to said magnetic field, each said electric field being maintained at the same polarity, the said apparatus being characterized by means for impressing electric fields including at least a pair of oppositely disposed expanders, the are being produced near the region betwen said expanders near one end of the region between them.

14. Apparatus according to claim 7 characterized by the fact that the curve of at least one expander at least approximately satisfies the equation where s is the distance along said expander from the end where it is nearest the other expander, x is the distance between the expanders measured along a line perpendicular to the center line between them, k is a constant and d is the difierential operator.

15. Apparatus for separating isotopes of a material including an evacuated container, means for producing in said container an are including ions of said isotopes, means for impressing a magnetic field generally parallel to said are, a pair of oppositely disposed expanders having their surfaces generally parallel to said are, said expanders extending radially from said are for impressing an electric field between said expanders, the vectors representing said last-named electric field lying in planes generally perpendicular to said magnetic field, said lastnamed electric field being maintained at a constant, polarity, and means for celleeting the isotopes produced by the interaction of said are and said last-named field, the said apparatus being characterized by collecting means including a plurality of slats with their planes extending generally radially with respect to said are as a center.

No references cited. 

